Seasonic X-Series 660W Power Supply Review

1. Introduction2. Seasonic X-Series 660W (Bundle & Cables)3. Seasonic X-Series 660W (External)4. Seasonic X-Series 660W (Internal)5. Seasonic X-Series 660W (Super High Res Gallery)6. Testing Methodology and Results7. Closing Thoughts8. View All Pages

Additional technical assistance: Peter McFarland and Jeremy Price.

Correctly testing power supplies is a complex procedure and KitGuru have configured a test bench which can deliver up to a 2,000 watt DC load. Due to public requests we have changed our temperature settings recently – previously we rated with ambient temperatures at 25C, we have increased ambient temperatures by 10c (to 35c) in our environment to greater reflect warmer internal chassis conditions.

We use combinations of the following hardware:
• SunMoon SM-268
• CSI3710A Programmable DC load (+3.3V and +5V outputs)
• CSI3711A Programmable DC load (+12V1, +12V2, +12V3, and +12V4)
• Extech Power Analyzer
• Extech MultiMaster MM570 digital multimeter
• SkyTronic DSL 2 Digital Sound Level Meter (6-130dBa)
• Digital oscilloscope (20M S/s with 12 Bit ADC)
• Variable Autotransformer, 1.4 KVA

We are combining 12V output into a single result.

DC Output Load Regulation
Combined DC Load	+3.3V		+5V		+12V		+5VSB		-12V
	A	V	A	V	A	V	A	V	A	V
152W	2.04	3.32	2.05	5.03	10.12	12.11	0.50	5.03	0.20	-12.02
270W	3.02	3.32	3.01	5.02	19.12	12.10	0.50	5.03	0.30	-12.03
400W	4.04	3.31	5.05	5.00	29.19	12.07	1.00	5.02	0.30	-12.05
523W	6.05	3.30	7.03	5.00	38.17	12.04	1.50	5.01	0.30	-12.08
652W	8.05	3.28	9.03	4.99	48.01	12.00	2.50	5.00	0.30	-12.10

Voltage regulation scores in the top 5% of results, maintaining well across all output stages.

Seasonic X-Series 660W	Maximum Load
	807.4W

The power supply delivered 807W before it would shut down safely – Seasonic are clearly over specifying these units as they all produce significantly more power than their rated output. While not recommended long term, this power supply can hold 800W without any issues for quite some time.

Next we want to try Cross Loading. This basically means loads which are not balanced. If a PC for instance needs 500W on the +12V outputs but something like 30W via the combined 3.3V and +5V outputs then the voltage regulation can fluctuate badly.

Cross Load Testing	+3.3V		+5V		+12V		-12V		+5VSB
	A	V	A	V	A	V	A	V	A	V
590W	1.0	3.32	1.0	5.02	48.0	11.99	0.2	-12.03	0.50	5.02
145W	12.0	3.28	15.0	4.98	2.0	12.10	0.2	-12.01	0.50	5.01

The Seasonic X-Series 660W exhibited no problems when dealing with this intensive set of Cross loading figures. It was hit with 48A on the +12V rail and held at close to 12.00V. The other rails also delivered remarkable results.

We then used an oscilloscope to measure AC ripple and noise present on the DC outputs. We set the oscilloscope time base to check for AC ripple at both high and low ends of the spectrum. ATX12V V2.2 specification for DC output ripple and noise is defined in the ATX 12V power supply design guide.

ATX12V Ver 2.2 Noise/Ripple Tolerance
Output	Ripple (mV p-p)
+3.3V	50
+5V	50
+12V1	120
+12V2	120
-12V	120
+5VSB	50

Obviously when measuring AC noise and ripple on the DC outputs the cleaner (less recorded) means we have a better end result. We measured this AC signal amplitude to see how closely the unit complied with the ATX standard.

AC Ripple (mV p-p)
DC Load	+3.3V	+5V	+12V	5VSB
152W	5	5	15	10
270W	5	5	20	10
400W	10	10	20	15
523W	10	15	25	15
652W	15	15	30	15

Noise suppression is excellent, peaking at 30mV on the +12V rail under full load. The other rails peak at 15mV at full load. These results are well within rated industry tolerance ratings.

Efficiency (%)
152W	84.03
270W	91.24
400W	91.01
523W	89.67
652W	88.81

Efficiency is very good, peaking over 91 percent at 50 percent load. At full load this drops to just below 89 percent.

We take the issue of noise very seriously at KitGuru and this is why we have built a special home brew system as a reference point when we test noise levels of various components. Why do this? Well this means we can eliminate secondary noise pollution in the test room and concentrate on components we are testing. It also brings us slightly closer to industry standards, such as DIN 45635.

Today to test the Power Supply we have taken it into our acoustics room environment and have set our SkyTronic DSL 2 Digital Sound Level Meter (6-130dBa) one meter away from the unit. We have no other fans running so we can effectively measure just the noise from the unit itself.

As this can be a little confusing for people, here are various dBa ratings in with real world situations to help describe the various levels.

KitGuru noise guide
10dBA – Normal Breathing/Rustling Leaves
20-25dBA – Whisper
30dBA – High Quality Computer fan
40dBA – A Bubbling Brook, or a Refridgerator
50dBA – Normal Conversation
60dBA – Laughter
70dBA – Vacuum Cleaner or Hairdryer
80dBA – City Traffic or a Garbage Disposal
90dBA – Motorcycle or Lawnmower
100dBA – MP3 Player at maximum output
110dBA – Orchestra
120dBA – Front row rock concert/Jet Engine
130dBA – Threshold of Pain
140dBA – Military Jet takeoff/Gunshot (close range)
160dBA – Instant Perforation of eardrum

Noise (dBA)
152W	<28.0
270W	29.3
400W	30.6
523W	32.7
652W	33.2

Generally this power supply is completely inaudible, especially when the system is resting idle. Even at 50% load, it can barely be heard and is likely to be drown out with chassis fans. Above 500W load, the fan spins up fairly actively, although noise levels are still low. At full load, the fan is audible, but not intrusive.

Temperature (c)
	Intake	Exhaust
152W	36	38
270W	37	41
400W	38	45
523W	42	47
652W	44	51

The large fan is perfectly capable of maintaining a very good thermal curve, peaking at only +7c above ambient threshold at full load.

Maximum load	Efficiency
807.4W	86.12

Pushing the PSU above its rated limits generates an ultimate efficiency level of around 86.5%. This is not a viable ‘real world’ situation, but its interesting nonetheless.

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